Determining position of vessels.



Ii. A. FESSENDEN.

' 05. 1,002,141 Patented Aug. 29, 1911. 2 SHEETS-SHEET 1.

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DETERMINING POSITION OF VBSSELS.

APPLICATION FILED AUG. 21, 1905.

1,002, 141 Patented Aug. 29, 1911.

2 SHEETS-SHEET 2.

FIE-1-2- WITNESSESL I NVEN'I'OR fiw mm Atty Unrr STATES ATENT OFFIQ.

REGINALD A. FESSENDEN, OF WASHINGTON, DISTRICT OF COLUMBIA, ASSIGNOR TO THE NATIONAL ELECTRIC SIGNALING COMPANY, OF PITTSBURG, PENNSYLVANIA,

A CORP CRATION OF NEW JERSEY.

DETERMINING POSITION VESSELS.

Specification of Letters Patent. Patented Aug. 1911.

Original application filed December 4, 1904, Serial No. 236,861. Renewed March 18, 1907, Serial No. 363,106. Divided and this application filed August 21, 1905. Serial No. 275,164.

To all whom it may concern:

Be it known that I, REGINALD A. Fnssnn- DEN, a citizen of the United States, and resident of WVashington, District of Columbia, have invented certain new and useful Improvements in Determining the Pos1tion of Vessels, of which the following is a specification.

The invention herein described relates to means for locating the position of ships at sea more especially during nighttime and cloudy or foggy weather.

In the accompanying drawings forming a part of this specification Figure 1 is a diagrammatic View illustrating my improved method, and Fig. 2 is a diagrammatic view illustrating a form of apparatus for giving standard signals.

For the practice of my invention I employ two or more wireless stations located at fixed points such as lighthouses or light ships. The vessel whose position is to be determined also carries a wireless apparatus. Signals are sent out, preferably at regular intervals, by the fixed station and in the method herein described the vessel locates a position by comparing the strength of the signals received either relatively or absolutely. While I do not limit myself to either method, it is preferred not to depend entirely upon the absolute measurements because of the serious consequences which may result, but to compare the intensity of the signals either relatively to each other or else relatively to each other and to a source of fixed strength located on board the vessel.

If absolute measurement of intensity is depended upon alone, any defect in the apparatus which may cause thesignals to have less intensity than they properly should would result in the ships being located much closer to land than she really was and hence this method, while it may be used, is preferably not relied upon entirely but is checked by the use as above mentioned of a standard on board the vessel and preferably also by comparison of the relative strengths of the signals from the fixed stations.

In the practice of my invention A, B, and C are wireless stations situated on the coast. These stations are preferably equipped with both sending and receiving apparatus. The sending apparatus is preferably automatic in its action but at least automatic during a part of the time, so that predetermined sig nals may be sent continuously or atpredetermined intervals in a manner similar to changes now effected in coast lights or audible signals. For example, station C may be arranged to send by clock-work suitable signals, as numerals 1, 2, 3, 4:, 5, 6, and 7, repeated continuously, at predetermined time intervals, or sent out in any desired manner. During intervals between signals or series of signals the station may be put in a receiving condition. The signals may be differentiated in any other desired manner, for example by being of different electrical or differentgroup tunes and may cause the same or different receivers or indicating mechanisms on board the vessel to respond. Instead of numerals any other arbitrary or well-known signals may be used. The strength of the signals is preferably varied so as to form a succession of gradually varying intensity and preferably so that each signal shall be readable or shall produce the same intensity at a point a given number of miles, for example, twenty miles farther or nearer from the station than the signal immediately preceding it. For example signal 1 may be readable at a distance of twenty'miles, signal 2 at forty, signal 8 at sixty and so on up to any desired distance. Preferably, however, the strength of the signals is arranged so that they shall not be readable more than three or four hundred miles from shore, though the same stations may emit other signals of greater or less intensity for other purposes. Similarly the station B emits a succession of signals, for example, 8, 9, 10, 11, 12, 13 and 14 which may be of a different tune or group frequency from those of station 0 but are preferably on the same tune and vary in intensity in the same way. These signals may be emitted simultaneously with those of station C but are preforably emitted immediately after the conclusion of the sending of signals of stat-ion C, and to this end the sending mechanism at the several sending stations may be adjusted to send signals at predetermined time noninterfering intervals. Similarly the third stationA may be similarly arranged to send out signals 15 to 21 or otherwise differentiated from the signals from other stations.

Where the sending of the signals 'of the station is arranged so that the groups of signals follow each other at predetermmed intervals, these intervals are easily deterif the apparatus is in good order, or else the point at which the signal 21 will have a strength equal with that given by the standardizing apparatus, if the latter be so arranged. This standardizing apparatus may consist of an auxiliary apparatus causing a signal of a given strength. This would normally indicate that the vessel was 140 miles away from station A but the exact direction would not be known. It may be, however, that some portion of the receiving apparatus, for example the antennae on the ship may not be in good condition in which case the ship may really be closer in. On the ships reaching the point E if the apparatus is in good order signals 12 and 19 will each be of equal intensity with thestandardizing signal, or if no standardizing signal is used will be of equal intensity wlth each other. If the signals 12 and 19 have intensities equal to that of the corresponding standardizing signal the distances and directions of the stations A and B from the ship are determined. But if no standardizing apparatus is used and the signals from A and B are compared and found to be of equal intensities the direction but not the exact distances of the stations from the ship is determined. On the ship reaching the point G, by the use of the standardizing apparatus we not only obtain the distance and direction from A and B but also havea check and determination of the distance from B to C three sets of signals 2'. 6., 5, 10 and 20 are now received of equal intensity with the standard. Even if the standardizing apparatus were not used or were out of order it is still possible to locate the position of the vessel, because there is only one point possible for the ship to occupy at which signals 5, 10 and 20 are of equal relative intensity.

By the above mentioned method it is possible for a ship to determine her position Without taking an observation and during night time or fog.

Instead of sending the seven signals successively they may be sent simultaneously andon different wave frequencies or tunes.

Various modifications will suggest themselves to those skilled in the art and the method-herein described is capable of being used with many different forms of apparatus but preferably with the form of apparatus described though the method is not limited to the use of such apparatus, as a great number of permutations and combinations can be made each of which may have its particular advantages in certain cases but which advantages are well known to those skilled in the art.

'ing the antenna produce indications of a certain strength in the indicator 29.

The coil 27 has one end connected with a capacity 31 and the other end with a com- .mutator 32, having brushes 33 and 34 and preferably driven by a motor 35 in such a Way that as the commutator revolves it charges the condenser 31 to a given voltage, determined by the position of the sliding contact 36 on the potentiometer 30, and then as the commutator revolves further it discharges the condenser 31 through the coil 27. This discharge through the coil 27 produces currents in the coils 26, 24 and 25 and thereby affecting the receiver 28 producing an indication on the indicator 29 depending upon contact 36.

The potentiometer is preferably provided the position of the sliding with a scale 39 and so designed that the indications produced at the different positions of the sliding contact-36 correspond in intensity to the series of signals sent out by the shore stations, as indicated on the 'scale 1 (Fig. 2). 1

An alternative method of varying the intensity of the signals is to adjust the distance between the coils 26 and 27, or to vary the capacity of the condenser 31. It is preferred, however, to arrange the variation permanently by means of a potentiometer 30.

Where the electromagnetic waves to be received are of diiferent frequencies or tunes it is preferred to make the capacity 31 adjustable so that the oscillating circuit containing the capacity 31 and coil 27 can have its oscillation frequency varied as desired. A pref- .erable means of accomplishing this result is, however to keep the capacity 31 constant and use a variable inductance 37 as shown in Fig. 2. When a variable inductance is used the amount of energy in each discharge isstations, Whether on land or ships, the presence in the neighborhood of other vessels. The signals from a ship can be of a definite character, either as regards the kind of signal, its intensity or -the time interval between signals or a succession of signals, so that by the receiptof such signals by another station on ship or land, the presence of a particular vessel will be known. In case of two vessels having signaling apparatus, approaching each other in a fog and emitting signals, a comparison of the received signals w1th the standardizing appa-' ratus will indicate to each vessel the distance of the other vessel from it and precautions can be easily taken to prevent any accident, and the character of the signal will'indicate the names and kinds of vessels in proximity to each other. Of course the mere receipt of signals by one vessel from the other vessel will not indicate'direction but only distance, and also whether vessels are approaching or going away from each other.

The method herein described is claimed in my co-pending application No. 236,861, filed Dec. 14, 1904, and renewed March 18th, 1907, as No. 363,106, of which application this is a division.

I claim herein as my invention,

1. Apparatus for'determining the position of vessels, comprising a series of fixed stations having means to send out signals of predetermined character, a receiving device on the vessel adapted to receive said signals,

and a means to measure their intensity as received, relative to. a standard signal of known character. I

' 2. Apparatus for determining the position of vessels, comprising a series of stations having means to send out signals of predeterminedintensity, means on the vessel to receive said signals, and-auxiliary means by which the relative intensityof the received signals may be measured.

3. In apparatus for determining theposition of vessels by electro-magnetic signals sent from fixe stations, a receiver for such electro-magnetic signals and a supplemen tary apparatus on the vessel for producing similar signals of predetermined known character, and means for comparing the character of the signals received with those from the fixed stations. l

4. In signal receiving apparatus the combination with an antenna and an adjustable receiving circuit, of a secondary oscillating circuit connected to said antenna whereby signals maybe simultaneously received on the antenna from outside and from said secondary circuit, and means for comparing the relative characters of said signals.

5. The combination with a series of stations of known position for sending signals of predetermined character, of a portable apparatus for receiving the signals, a connected supplementary apparatus for producing similar signals of known character, and means to compare the characters of the signals received from the said two sources.

REGINALD A. FESSENDEN.

Witnesses;

Jnssm E. BENT, J. F. BUCKLEY. 

